The amount of heat needed to increase the temperature of a substance by
is given by
where
m is the mass of the substance
the specific heat capacity
the increase in temperature
In our problem, the mass of the water is m=750 g, the specific heat is
and the amount of heat supplied is
, so if we re-arrange the previous formula we find the increase in temperature of the water:
Answer:
Therefore the surface area of the balloon is increased at 4 cm³/s.
Explanation:
The balloon is being filled with air at a rate of 10 cm³/s
It means the volume of the balloon is increased at a rate 10 cm³/s.
i.e 
Consider r be the radius of the balloon.
The volume of of a sphere is
Differentiate with respect to t
The surface of area of the balloon is(S) = 
Differentiate with respect to t
Putting the value of 
Given that r = 5 cm
![[\frac{dS}{dt}]_{r=5} =\frac{20}{ 5}](https://tex.z-dn.net/?f=%5B%5Cfrac%7BdS%7D%7Bdt%7D%5D_%7Br%3D5%7D%20%3D%5Cfrac%7B20%7D%7B%205%7D)
=4 cm³/s
Therefore the surface area of the balloon is increased at 4 cm³/s.
Answer : 413.44N
Here it is given that an elevator is moving down with an acceleration of 3.36 m/s² . And we are interested in finding out the apparent weight of a 64.2 kg man . For the diagram refer to the attachment .
- From the elevator's frame ( non inertial frame of reference) , we would have to think of a pseudo force.
- The direction of this force is opposite to the direction of acceleration the frame and its magnitude is equal to the product of mass of the concerned body with the acceleration of the frame .
- When a elevator accelerates down , the weight recorded is less than the actual weight .
From the Free body diagram ,
- Mass of the man = 64.2 kg
Answer:
8000J
Explanation:
The kinetic energy of the car lost during breaking are converted to thermal energy and are gained by the brakes.
Kinetic energy loss by car = thermal energy gained by brakes.
∆K.E = ∆T.E ....1
The Kinetic energy loss by car can be expressed as;
∆K.E = K.E1 - K.E2
Initial K.E = K.E1 = 10000J
Final K.E = K.E2 = 2000J
∆K.E= 10000J - 2000J = 8000J
From equation 1,
∆K.E = ∆T.E
∆T.E = 8,000J
thermal energy gain by brakes = 8,000J
Answer:
Explanation:
Speed = Distance / Time
So, to find distance, we actually divide distance by rime.
